Nanotech positioned to put food testing in “palm of consumers’ hands”

05 Jul 2021 --- Consumers may soon be able to assess the maturity or microbial decomposition of food with their smartphone, thanks to a portable spectrometer. Researchers at the Fraunhofer Institute for Electronic Nano Systems (ENAS) in Germany designed the device for quick, cost-effective and straightforward testing, including for food. 

The spectrometer can also detect pollutants in air, water or foodstuffs.

“Our infrared spectrometer weighs only about a gram and we plan for it to cost less than a euro to produce,” says Dr. Alexander Weiß, head of the department of multi device integration at Fraunhofer ENAS. 

“This will allow it to be integrated into smartphones, for instance.” 

The aim is ultimately to mass-produce the device using conventional technologies. If further investigations go as hoped, the spectrometer could be on its way to the mass market in as little as two years.

Building off a current technology 
At present, infrared spectrometers weigh several kilograms and cost thousands of euros to produce. 

“Conventional spectrometers usually consist of discrete more or less well-integrated components. We, on the other hand, integrated the beam guidance, the splitting of the individual wavelengths and the detection function in one plane. We are therefore also calling this an “inplane spectrometer,” explains Weiß.

Although transportable devices weighing slightly less do exist, they are unsuitable for the mass market, both in terms of cost and size and also in terms of operation and analyzing the results. 

Measurement setup with wafer prober, optical fiber probes and wafer with test structures.Just like conventional infrared spectrometers, this spectrometer does this by emitting light beams in the infrared range. The light of different wavelengths is then fragmented using a tunable filter and conducted to a detector by means of integrated waveguides. 

Grating couplers with nanostructures bundle the light reflected by a pill to be tested, for example, into integrated waveguides. If the air quality is to be tested, the light enters a special absorption cell integrated in one plane instead. 

“If we plot how much light reaches the detector at which wavelength, we get a characteristic spectrum that is different for each sample, similar to a fingerprint,” says Weiß.

The mainstreaming of such technology could put more information into consumers’ hands for everything that they consume, including food and medicine. 

For example, pills purchased online can be tested for counterfeit composition. A fake pill, with different ingredients, has a different spectrum to that of the original drug.

Bringing to the masses
Other requirements crucial to existing on the mass market: The technology must not be overly complex – in other words, it must be easy to operate – and the production method must be suitable for the mass market.

Operation must be easy and intuitive and the system must then provide the user with clear evaluations. The researchers have already developed a concept: Smart learning algorithms. 

The spectrometer can detect pollutants in air, water or foodstuffs.“If many people use the technology, the system will learn quickly,” says Weiß. 

“The user will simply need to pull out their phone, start the spectrometer via a special app and hold it over the sample. They will also see an instruction that guides them through the measurement process. The spectrometer generates the spectrum automatically and the software compares it to reference spectra entered into a database by specialists beforehand.” 

The more people who come to use the system, the greater the possibility for making comparisons.

Another sticking point is the cost of producing the spectrometer. The researchers had this in mind from the outset too. “We designed the spectrometer in a way that would allow it to be mass-produced inexpensively using conventional microsystems engineering technologies. Manufacturers can use the processes that are standard on the large fabrication lines, fabs for short,” explains Weiß.

The researchers have already produced the first spectrometer chips and provided proof of concept. A number of different characterizations are now on the agenda: Do the individual components move as we want them to? Is the light that is coupled into the waveguide transmitted as it should be? The equipment required for these characterizations has been financed by the Research Fab Microelectronics Germany.

Edited by Missy Green

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